Research Of Genetic Algorithm Applied In Beamforming Technology Based On Subarray

In underwater acoustic signal processing field, beam forming technology, especially multi-beam is often used. How to get the desired signal in the expected direction for a base array is the purpose of sonar beamforming. These can be generally understood from two aspects. The emission energy is concentrated in a certain direction, so that for the same transmission power of the sonar system, the effect will be obtained relatively at a good distance. For the receiver, the target can be identified better. On the receive side, if there are more than one goal,with target specific to a certain direction,multi-beam is a good choice.Conventional single beam sonar receiving and transmitting process only use single coverage.The multi-beam sonar system preformed well,covering a larger fan,so multi-beam forming technology is applied in the field of underwater acoustic. The main resesrch contents in this thesis are as follows.Firstly, the paper discusses the research background and significance, research status of array signal processing and beamforming technology, beamforming classification and basic array model knowledge. This Paper also focuses on the basics of beamforming and weighting methods.Secondly, the paper briefly describes the research and simulations of uniform non-overlapping subarrays,uniform overlapping subarrays and non-uniform non-overlapping subarray. Under conditions of mastering the subarray division effects of beamforming,how the subarray overlapping affects beamforming performance is also discussed.Then, the paper studies basics of subarray digital multi-beam forming technology and accomplish subarray weighted multi-beam and FFT multi-beam forming research. Either non subarray designing methods or subarray designing methods are described. From the simulation results, the problems and disadvantages are put forwards.Finally, according to the problems encountered before, a method using genetic algorithm to find analog and digital weight coefficients of the array is analyzed. Because the traditional genetic algorithm is unstable occasionally, niche genetic algorithm is studied to improve the traditional genetic algorithm. The usage of niche genetic algorithm which is the extension of the traditional genetic algorithm proposes a new concept for subarray multi-beam forming technology.